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A233211
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Number of n X 2 0..5 arrays with no element x(i,j) adjacent to value 5-x(i,j) horizontally or antidiagonally, top left element zero, and 1 appearing before 2 3 and 4, and 2 appearing before 3 in row major order.
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1
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2, 23, 452, 10313, 249062, 6147803, 152986472, 3818284493, 95399716682, 2384476356383, 59607259863692, 1490139655179473, 37253114806771502, 931324481014849763, 23283081522981304112, 582076763553023143253
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OFFSET
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1,1
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LINKS
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FORMULA
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Empirical: a(n) = 35*a(n-1) - 259*a(n-2) + 225*a(n-3).
G.f.: x*(2 - 47*x + 165*x^2) / ((1 - x)*(1 - 9*x)*(1 - 25*x)).
a(n) = (75 + 10*9^n + 3*25^n) / 120.
(End)
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EXAMPLE
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Some solutions for n=5:
..0..0....0..1....0..0....0..0....0..0....0..0....0..0....0..1....0..0....0..0
..1..1....0..2....1..2....1..0....1..5....1..0....0..1....0..2....0..1....0..1
..0..0....4..4....0..2....2..0....2..0....2..0....5..2....1..1....2..5....2..4
..2..1....0..0....2..2....1..0....2..4....1..0....1..3....1..3....2..4....4..2
..1..5....3..3....5..3....4..5....5..2....1..5....0..4....1..3....0..4....1..5
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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